Performance issue on broadcasting message

I got a user group with almost 3,000 users. When I broadcast to this group via the broadcast plugin. Yes, it worked but the whole broadcast process toke 1 minute to finish. During this period, no other messages could be delivered. Is there any way to improve the performance? Anybody can share your experience. Thanks in advanced.

One more thing, I am using Linux based Openfire server with 8GB RAM, latest server model and dedicated MSSQL server with the same hardwar configuration.

Not only broadcasting message will hold up the message queue but also will affect new user login. I recently found that while the server is handling the broadcast message via broadcast plugin, the server will not accept any new user login for a short period.

Anybody experienced the same problem and what is your solution. Please help.